Method for conversion of ethylidene N,N'-bis-pyrrolidone into 2-pyrrolidone

Abstract

A method for conversion of ethylidene N,N'-bis-pyrrolidone, a by-product of the vinylation of 2-pyrrolidone, into 2-pyrrolidone starting material. This method is carried out by heating the by-product at an elevated temperature for a predetermined period of time, and recovering the 2-pyrrolidone conversion product therefrom for recycle into the vinylation process.

What is claimed is: 
     
       1. A process for converting ethylidene-N,N'-bis-pyrrolidinone into 2-pyrrolidone which comprises pyrolyzing said ethylidene-N,N'-bis-pyrrolidinone at an elevated temperature. 
     
     
       2. A process according to claim 1 wherein said temperature is about 120° to 300° C. 
     
     
       3. A process according to claim 2 which is carried out for about 0.01 to 48 hours. 
     
     
       4. A process according to claim 3 in which at least a 10% conversion is obtained. 
     
     
       5. In a process of vinylation of 2-pyrrolidone with acetylene in the presence of a strongly basic catalyst, the step of converting the ethylidene-N,N'-bis-pyrrolidone by-product of said vinylation process into 2-pyrrolidone by pyrolysis of said ethylidene-N,N'-bis-pyrrolidone at about 120° to 300° C. for subsequent use as starting material in said process. 
     
     
       6. A process according to claim 5 wherein said pyrolysis is carried out in a batch process. 
     
     
       7. A process according to claim 5 wherein said step is carried out by continuously flowing said ethylidene-N,N'-bis-pyrrolidone through a hot tube. 
     
     
       8. A process according to claim 5 wherein said 2-pyrrolidone is recycled into the vinylation process. 
     
     
       9. A process according to claim 5 which is carried out for about 0.01 to 48 hours.